The easiest way to block unwanted incoming calls in case if your phone has a built-in function is "Black list". Read the manual of your phone and enable the feature following the instructions.
In smartphones Nokia, even if such built-in feature yet, implement a "Black list" programmatically. On the Internet you can find lots of free software such as Call Manager, Advanced Call Manager, MCleaner. Ask, is it compatible software with the model of your smartphone, download it and install as an application. The subscriber, which will be included in your "Black list", dialing your number, will be able to hear just a beep "busy".
If you are a subscriber of "MegaFon" or the "Skylink" install the service "Black list" by contacting the offices of these companies or the operators of adding text and short number on which it will be necessary to send an sms message. This service is free, but costs cheap monthly payment is about 30 rubles.
But the owners of ordinary, not multifunction devices Nokia do not despair. Create the menu "Contacts" group, which includes those subscribers communicate with whom you want to avoid. In the settings group, check the melody "sound off" and calls from them you will be heard. However, in the "Unanswered call" will be a list of those phones, which owners have failed to hear your "Hello!".
On a normal Nokia phone to block the incoming call will fail but you can use the function redirect. Change the setting to redirect any non-existent phone number, for example, consisting of a smaller number of digits. And unwanted companion will constantly hear the tube: "the number you have Dialed does not exist".